This is an MCP3422 (16 bit, 2 channel differential, 0-7V, I2C) on one of dipmicro's adapters. Somehow I soldered this one OK but don't think I'll buy these adapters again. You'll have to forgive me for going pretty light on the solder on those pin headers.

Nice chips/breakout boards. I'm still looking for easy to use bipolar ADC to measure +-10V range. Too bad these ones are unipolar.

May I suggest the use of a custom-made ADC driver chip from Analog Devices for this purpose? The 8275 will not only take that bipolar input and reduce the output to 0-4VDC, it'll also create a nice signal centered around 2VDC, perfect for differential ADCs with unipolar inputs.

May I suggest the use of a custom-made ADC driver chip from Analog Devices for this purpose? The 8275 will not only take that bipolar input and reduce the output to 0-4VDC, it'll also create a nice signal centered around 2VDC, perfect for differential ADCs with unipolar inputs.

Do you think that chip would work with a guitar? My guitar outputs .7volts AC rms . I need a high impedance amplifier to make the guitar signal compatible with the Due input. I would like the level centered at 1.5V with about 1.5V swing.

There's a DIY pre-amp circuit shown on this short youtube. Maybe it will help?

https://www.youtube.com/watch?v=aOJuCYgmPPE

Thank you, I think that circuit will only work for a piezo but, it put me on a better track for finding a circuit design. After following your link, I found some other sites that have some ideas that may work.

I suggest you take a look at the Analog Devices and TI web sites. Both offer a wealth of information re: op-amps and from the looks of it, your application is tailor-made for an op-amp. You could go for a G=1.5 circuit that simply shifts the signal from +/- 0.7Vrms to 1.5VDC +/- 1.5Vpp. That would result in a signal from 0-3VDC, well within the specs of the Due ADC. Plus, you gain the benefit of a low-impedance source, i.e. one that will make the ADC inside the Due very very happy.

Then I put in one of the 24 MHz crystals that I also ordered (because dhenry claimed you could clock it at 24 MHz) and it output at 14400 baud (9600 * 24 / 16 = 14400). So on the face of it, you can run at higher speeds. Now I can't say for sure that it is working perfectly, but after running for 10 minutes or so, the ASCII table is still coming out.

Trap for young players: I initially saw no output, which I spent 15 minutes mucking around trying to fix, until I realized the sketch only outputs the table once. At 24 MHz that doesn't take long!

Please post technical questions on the forum, not by personal message. Thanks!